Cisco Unified Border
Element (CUBE) is network border element that can terminate and originate
signaling (H.323 and Session Initiation Protocol [SIP]), media streams
(Real-Time Transport Protocol [RTP] and RTP Control Protocol [RTCP]).
controller (SBC) was used by service providers (SP) to enable full billing
capabilities within VoIP networks. CUBE provides the extended functionality of
interconnecting VoIP networks, especially on the enterprise side.
is implemented on devices using a special IOS feature set, which allows CUBE to
route a call from one VoIP dial peer to another. As VoIP dial peers can be
handled by either SIP or H.323, CUBE can be used to interconnect VoIP networks
of different signaling protocols. VoIP internetworking is achieved by
connecting an inbound dial peer with an outbound dial peer. A standard Cisco
IOS gateway without CUBE functionality cannot allow VoIP-to-VoIP connections.
Protocol internetworking is possible for the following combinations:
- H.323-to-SIP internetworking
- SIP-to-SIP internetworking
CUBE is used by
enterprise and small and medium-sized organizations to interconnect SIP PSTN
access with SIP and H.323 enterprise unified communications networks.
A CUBE interoperates
with several different network elements including voice gateways, IP phones,
and call-control servers in many different application environments, from
advanced enterprise voice and/or video services with Cisco Unified
Communications Manager or Cisco Unified Communications Manager Express, as well
as simpler toll bypass and voice over IP (VoIP) transport applications. The
CUBE provides organizations with all the border controller functions integrated
into the network layer to interconnect unified communications voice and video
Figure 1. Cisco Unified
Border Element—More than an SBC
The CUBE provides a
network-to-network interface point for:
interworking—H.323 and SIP.
interworking—dual-tone multifrequency (DTMF), fax, modem, and codec
- Address and port
translations—privacy and topology hiding.
- Billing and call detail
record (CDR) normalization.
- Quality-of-service (QoS)
and bandwidth management—QoS marking using differentiated services code point
(DSCP) or type of service (ToS), bandwidth enforcement using Resource
Reservation Protocol (RSVP), and codec filtering.
Figure 2. Why does an
enterprise need the CUBE?
The Session Initiation Protocol (SIP) is a signaling communications protocol, widely used for controlling multimedia communication sessions such as voice and video calls over Internet Protocol (IP) networks. SIP (or H.323) trunking is the use of VoIP to facilitate the connection of a private branch exchange (PBX) to the Internet. To use SIP trunking, an enterprise must
have a PBX that connects to all internal end users, an Internet
telephony service provider (ITSP) and a
that serves as the interface between the PBX
and the ITSP. One of the most significant advantages of SIP
trunking is its ability to combine data, voice, and video in a
single line, eliminating the need for separate physical media for
Figure 3. SIP/H.323 Trunking
SIP trunking overcomes TDM barriers, in that it:
- Improves efficiency of interconnection between networks
- Simplifies PSTN interconnection with IP end-to-end
- Enables rich media services to employees, customers, and partners
- Carries converged voice, video, and data traffic
Figure 4. SIP Trunking overcomes TDM Barriers